Magnetic field shimming, measurement and control for the BNL muon (g-2) experiment

An ultraprecise superferric magnet, 14 m in diameter, was built for the muon (g-2) experiment currently in progress at Brookhaven National Laboratory. The principal quantities to measure in the experiment are the frequency of (g-2) oscillations and the average magnetic field, which imply stringent requirements on the homogeneity of the magnetic field as well as on the precision of its measurement and control system. This paper describes (g-2) magnet, shimming techniques used to improve it and advanced NMR and Hall probes systems to measure and monitor magnetic field.